input{
    width: 400px;
}
.chang{
    width: 100px;
}
body{
    width: 100%;
    height: 100%;
}
.box{
    display: none;
    position: fixed;
    top: 0;
    height: 100%;
    width: 100%;
    background-color:gray;
    opacity: 0.8;

}
.box1{
    position:relative;
    width: 500px;
    top: 0;
    left: 0;
    background-color: #fff;
    cursor:pointer
}